x+y+z=2 2x-y+z=-1 x-y-z=0

x+y+z = 2 ......(1)
2x-y+z = -1 ....(2)
x-y-z = 0 .......(3)

Eliminasi y dari persamaan 1 & 2
x +y+z = 2
2x-y+z = -1
----------------- +
3x + 2z = 1 ....(4)

Eliminasi y dari persamaan 2 & 3
2x-y+z = -1
x -y -z = 0
---------------- -
x + 2z = -1 .....(5)

Eliminasi z dari persamaan 4 & 5
3x + 2z = 1
x + 2z = -1
----------------- -
2x = 2
x = 1

subtitusi x ke persamaan 4
3x + 2z = 1
3(1)+ 2z = 1
2z = 1-3
z = -2

Subtitusi x dan z ke persamaan 1
x + y + z = 2
3 + y +(-2) = 2
y + 1 = 2
y = -1

Maka, HP{ x= 1, y= -1, z= -2}